Hi@akhtar,
 In OpenStack you are the admin of your cloud, so you can create a public network in OpenStack. Follow the below given steps.
- 
Log in to the OpenStack dashboard as an administrator. 
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Verify the existence of external networks. For this, navigate to Project > Network > Network Topology. 
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Check the network type in network details. For this, navigate to Admin > Networks and see the Network name section. Alternatively, run the openstack network list --external command using CLI. 
- 
Navigate to Project > Network > Networks>create network 
Hope these steps help you.
Thank You